Human THP-1 cells expressing a catalytically-active RdRP display highly augmented antiviral defenses.

(A) Stable RdRP THP-1 cell lines were generated using lentiviral vectors that co-express GFP-puro with RdRP, RdRPΔcat, or no RdRP (null). (B) Heat map of differentially expressed genes in THP-1 monocytes, presented as fold change (blue = 1-fold induction; purple = 8-fold upregulation; red = ≥15-fold upregulation). RdRP: subset of antiviral genes significantly upregulated >4-fold in RdRP THP-1 cells (n = 2) compared with null empty vector control THP-1 cells (n = 2). RdRPΔcat: THP-1 cells expressing the RdRPΔcat transgene (n = 2) compared with null empty vector control THP-1 cells (n = 2). For a complete list of upregulated genes see S4 & S7 Tables. (C) THP-1 cell lysates were run in duplicate and analyzed by immunoblotting using antibodies to OAS2, MX1, and IFIT1. Antibody to HA-tag was used to determine relative abundance of RdRP-HA protein in each cell line. Antibody to β-ACTIN served as control, data are representative of two independent experiments. (D) Infection by an HIV-1 reporter virus (HIV-1luc) in RdRP, RdRPΔcat, and parental THP-1 cell lines. Data are mean ± SEM of three technical replicates, and are representative of two independent experiments.